NCVS data on juvenile crime victimizations reported to police and other authorities show that only 28 percent of violent crimes against juveniles become known to police. An additional 16 percent of violent crimes against juveniles are reported to some authority other than the police, mostly school officials. Juvenile victims are substantially less likely than adult victims to have their violent crimes reported to the police or any other authority. Violent sexual assault, although generally underreported, is one crime that is reported to police and other authorities about as often for juveniles as for adults. Only 10 percent of thefts against juveniles become known to police, but an additional 29 percent of such thefts are reported to other authorities, such as school officials. High-value thefts (more than $250) with juvenile victims are less likely to be reported to police or any other authority than those with adult victims. Juveniles report more low-value thefts (less than $50) to some authority than do adults, mostly to school officials. Given the high rate of juvenile crime victimization, its underreporting should be considered a significant problem that needs to be addressed by law enforcement policies. 1 table, 5 figures, and 5 references